Rotation resistant friction adapter for plunger driver of drug delivery device

ABSTRACT

A method and system are disclosed for driving a plunger in a drug reservoir. In some embodiments, a variable friction element interconnects between a pushing shaft and a wall of the reservoir. For example, rotation of a driving element in a first direction relative to the pushing shaft may advance the pushing shaft in the reservoir. The friction element may have increased friction resistance to rotation of the pushing shaft in the first direction in comparison to frictional resistance to advancing the pushing shaft. For example, the increased friction may result from wedging a radial element between the pushing shaft and the wall of the reservoir.

FIELD AND BACKGROUND OF THE INVENTION

The present invention, in some embodiments thereof, relates to an anti-rotational friction fitting, more particularly, but not exclusively, to a fitting for preventing rotation of a plunger driver of a drug delivery device.

U.S. Pat. No. 7,967,795 to the present inventor (Oz Cabiri) discloses “a cartridge interface assembly including a driving plunger including an outer shaft, and a driver including an inner shaft, the inner shaft mating with an intermediate shaft, the intermediate shaft mating with the outer shaft, so that the shafts are movable telescopically with respect to one another, wherein rotation of the driver causes the driving plunger to advance in a direction away from the driver”.

SUMMARY OF THE INVENTION

According to an aspect of some embodiments of the invention, there is provided an assembly for driving a plunger and in a drug reservoir, the plunger dividing between a drug in a distal portion of the reservoir and a proximal opening of the reservoir; the assembly comprising: a telescoping shaft that extends by rotation of a driving element in a first rotational direction with respect to a distal shaft; a distal end of the distal shaft configured to engage the plunger; and a radial element extending from the distal shaft to contact an interior side wall of the reservoir, the element configured and oriented to wedge between the interior wall and the distal shaft when the distal shaft is rotated in the first rotational direction.

According to some embodiments of the invention, the element includes a virtual sprag having a long axis and wherein the long axis intersects the interior side wall.

According to some embodiments of the invention, the long axis intersects the interior side wall at an angle between 91 and 120 degrees from the first rotational direction.

According to some embodiments of the invention, the element includes a virtual beam having a preferred bending direction opposite the first rotational direction.

According to some embodiments of the invention, the assembly further comprises: a plunger interface configured to engage the plunger; the plunger interface irrotationally interconnecting the distal shaft and the plunger when the plunger interface is engaged to the plunger.

According to some embodiments of the invention, the assembly further comprises: a vent for releasing gas from a space between the element and the plunger.

According to some embodiments of the invention, the radial element is located proximal to the distal end of the distal shaft.

According to some embodiments of the invention, the wedging is longitudinal such that moving the distal shaft distally with respect to the reservoir reduces a normal force between the radial element and the interior wall.

According to some embodiments of the invention, a resistance due to friction between the radial element and the interior wall to movement of the distal shaft in the first rotational direction is higher resistance due to friction between the radial element and the interior wall to movement of the distal shaft in a direction opposite the first rotational direction.

According to some embodiments of the invention, the assembly further comprises: a second friction element extending from a drug delivery device to contact an exterior side wall of the reservoir when the reservoir is inserted into the drug delivery device, the second friction element is configured and oriented to wedge between the exterior wall and the reservoir when the reservoir is rotated in a second rotational direction.

According to some embodiments of the invention, the second rotational direction is opposite the first rotational direction.

According to an aspect of some embodiments of the invention, there is provided a method of advancing a plunger in a drug reservoir comprising: providing a telescoping assembly that extends by rotating a driver in a first direction with respect to a pushing shaft mated to the driver, the pushing shaft including a friction element in contact with a wall of the reservoir; rotating the driver in the first direction; wedging the friction element between the pushing shaft and the wall as result of the rotating; inhibiting rotation of the first direction as a result of the wedging; and unwedging the friction element to facilitating advancing of the pushing shaft.

According to some embodiments of the invention, the wedging is substantially the only process impeding rotation of the pushing shaft with respect to the reservoir.

According to some embodiments of the invention, wedging include increasing normal force.

According to some embodiments of the invention, the method further comprises:

reducing a normal force between the friction element and the wall of the reservoir when the pushing shaft moves in a distal direction.

According to some embodiments of the invention, the drug reservoir includes a plunger, the method further comprising: reducing a normal force between the friction element and the wall of the reservoir when the pushing shaft pushes distally against the plunger.

According to an aspect of some embodiments of the invention, there is provided a drug delivery device comprising: a housing including a channel; a drug reservoir fitting into the channel; and a friction element extending from a housing to the channel to contact an exterior side wall of the reservoir when the reservoir is inserted into the channel, the element configured and oriented to wedge between the exterior wall and the reservoir when the reservoir is rotated in a first rotational direction.

According to some embodiments of the invention, the assembly further comprises: a telescoping shaft that extends by rotation of a driving element in a first rotational direction with respect to a shaft; and a second friction element inhibiting rotation of the shaft with respect to the reservoir.

According to some embodiments of the invention, the channel is cylindrical and includes an opening at one end and wherein the reservoir slides longitudinally through the opening into the channel and wherein the friction element has increased friction resistance to movement in the first rotational direction than to movement in the longitudinal direction.

According to an aspect of some embodiments of the invention, there is provided a method of distributing a drug comprising: supplying a reservoir containing the drug and a distribution device including a channel and a friction element; inserting the reservoir into longitudinally into the channel; and wedging the reservoir against the friction element by rotating the reservoir with respect to the device.

Unless otherwise defined, all technical and/or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the invention, exemplary methods and/or materials are described below. In case of conflict, the patent specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and are not intended to be necessarily limiting.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Some embodiments of the invention are herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of embodiments of the invention. In this regard, the description taken with the drawings makes apparent to those skilled in the art how embodiments of the invention may be practiced.

In the drawings:

FIG. 1 is a flow chart illustration of a method of facilitating movement of a plunger driver in accordance with embodiments of the current invention;

FIG. 2 is a flow chart illustration of a method of driving a plunger in accordance with embodiments of the current invention;

FIG. 3A is a block diagram illustration of an assembly for driving a plunger in accordance with embodiments of the current invention;

FIGS. 3B-3C are schematic diagrams of a sprag element resisting movement in a hindered direction and allowing movement in a direction other than the hindered direction in accordance with embodiments of the current invention;

FIGS. 4A-4F are drawings of a plunger driving assembly and drug reservoir with a threaded plunger interface in accordance with embodiments of the current invention;

FIG. 5 is a perspective driving of a plunger pushing rod and friction element for facilitating forward linear motion in accordance with embodiments of the current invention;

FIGS. 6A-6B are cross sectional views of a plunger pushing rod including flexible beam anisotropic friction elements in accordance with embodiments of the current invention;

FIGS. 7A-7B are side views of a plunger pushing assembly with reduced friction when engaged to a plunger in accordance with embodiments of the current invention;

FIG. 8 is a perspective view of a plunger pushing rod including a sprag friction elements and a ram plunger interface in accordance with embodiments of the current invention;

FIG. 9 is a perspective view of a plunger pushing rod including virtual sprag friction elements in accordance with embodiments of the current invention;

FIG. 10A is a perspective view of a cartridge including a wheeled friction element in accordance with an embodiment of the current invention;

FIG. 10B is a perspective view of a wheeled friction element with a shaft mount in accordance with an embodiment of the current invention;

FIG. 10C is a perspective view of a wheeled friction element without a shaft mount in accordance with an embodiment of the current invention;

FIG. 11 is a perspective view of a cartridge held by an external friction annular element in accordance with an embodiment of the current invention;

FIG. 12A is a perspective view of a cartridge including an external semi annular friction element in accordance with an embodiment of the current invention; and

FIG. 12B is a perspective view of a cartridge including an external semi annular friction element installed into a drug delivery device in accordance with an embodiment of the current invention.

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION OVERVIEW

The present invention, in some embodiments thereof, relates to an anti-rotational friction fitting, more particularly, but not exclusively, to a fitting for preventing rotation of a plunger driver and/or a reservoir of a drug delivery device.

An aspect of some embodiments of the present invention relates to a variable friction element facilitating forward movement of a plunger pushing shaft inside a drug reservoir. For example, forward motion of the pushing shaft may be driven by rotation of a driver element with respect to the pushing shaft. The friction element may facilitating the relative rotation for example by inhibiting the pushing shaft from rotating along with the driving element and/or by inhibiting rotation of the reservoir. Alternatively or additionally, the friction element may be designed to reduce friction to forward movement of the pushing shaft and/or reservoir (facilitating movement in the forward, preferred direction).

In some embodiments, the friction element may facilitate and/or speed up forward movement of the pushing shaft and/or plunger interface prior to contact with the plunger. Optionally, when the pushing shaft is pushing the plunger, resistance to forward movement due to the friction element may be reduced and/or may self-adjust to minimal and/or may be negligible.

As used herein the term plunger means a piston element. For example, a plunger may include a plunger shaft and/or a plunger head and/or a plunger seal and/or a mating element. As used herein, the term/phrase plunger seal means a piston element that impedes fluid flow. Optionally, plunger seal includes and/or is integral to a piston head. For example, the seal may have the form of a stopper and/or a gasket. In some embodiments, the term plunger may refer to the plunger seal alone. For example, the plunger may include a single sealing element that is pushed by a driver. Optionally, the driver may include a pushing shaft.

In some embodiments, the friction element is configured to wedge and/or increase a normal force between an outer wall of the shaft and an inner wall of the reservoir when the shaft moves in an inhibited direction with respect to the reservoir. In some embodiments, the friction element is configured to wedge and/or increase a normal force between an outer wall of the reservoir and a drug delivery device when the reservoir moves in an inhibited direction with respect to the delivery device. Alternatively or additionally, the friction element is configured to become dislodged and/or reduce a normal force between an outer wall of the shaft and in inner wall of the reservoir when said shaft moves in a preferred direction with respect to the reservoir. In some embodiments, the preferred direction of movement is in a direction that causes the rod to approach the plunger and/or discharge the drug, for example advancement, for example in the distal direction.

In some embodiments, the friction element may include a sprag and/or a beam. For example, a beam may have a preferential mode of bending that causes anisotropic friction. Optionally, the sprag and/or beam may include a separate element. Alternatively or additionally, the sprag and/or beam may be integral to another element and/or other elements. As used herein the term virtual element (for example virtual sprag and/or virtual beam) means an element that is intrinsic to another element. For example, a virtual sprag and/or beam may be a region of a radial element (for example the radial element may include a disk) having decreased compressibility in comparison to a surrounding region. For example, a virtual sprag and/or beam may include a rib on a radial element.

In some embodiments, a sprag may be an element that is propped between two surfaces at an angle such that a movement of one of the surfaces in first direction compresses the sprag and/or wedges the sprag between the two surfaces thereby increasing a normal force and/or a resistance to the movement. Alternatively or additionally, movement of the surface in a direction different from the first direction may reduce a normal force and/or decrease resistance to the movement and/or reducing resistance to another movement. A virtual and/or a combined sprag may include a portion of an element having properties that cause variable friction between two surface such that a movement in first direction compresses the sprag increasing resistance to the movement and/or a movement in a direction different from the first direction releases a force on the sprag decreasing resistance to the opposite movement and/or to any movement. For example, frictional resistance to movement in the inhibited direction may range between 2× to 4× as large and/or between 4× to 10× and/or between 10× to 100× or greater than 100× as great as frictional resistance to movement in an another direction (for example an opposite direction from the first direction) and/or as frictional resistance to movement in the preferred direction. For example, movement in the preferred direction may reduce frictional resistance to movement by 2× to 4× and/or by 4× to 10× and/or by 10× to 100× or greater than 100×. The combination of increasing frictional resistance to movement in a non-preferred direction while reducing frictional resistance to movement in a preferred direction may reduce and/or minimize friction resistance to movement in the preferred direction while increasing and/or maximizing resistance to other movements.

In some embodiments, a friction fitting and/or a plunger interface may include an air vent. The air vent may prevent buildup of an air pocket between the plunger interface and the plunger as the pushing shaft and/or plunger interface approaches the plunger.

In some embodiments, the friction element of the present invention may work with various forms of medicine reservoirs and/or plungers. For example, the invention may be configured for a standard syringe, cartridge, reservoir and/or plunger. For example, the cavity of the reservoir may be cylindrical. For example, the cavity of the reservoir may have smooth walls.

An aspect of some embodiments of the present invention relates to an element that produces high friction when the pushing shaft is moving with minimal external resistance and/or produces reduced friction when the pushing shaft is pushing against a plunger of the reservoir. For example, the plunger interface may be configured to cause the friction element to fold and/or bend away from the walls of the reservoir and/or reduce friction when the interface engages the plunger.

In some embodiments, the plunger interface may include a standard connector. For example, the plunger interface may include a screw that screws into the plunger. The interface may transfer linear force and/or rotational torque between the pushing shaft and the plunger. Alternatively or additionally, the interface may transfer linear force in one or more directions while transferring limited and/or negligible torque between the pushing shaft and the plunger. For example, a plunger interface may include a screw thread. Until the screw interface reaches the plunger, the friction element may inhibit rotation and/or facilitate linear movement of the pushing shaft. As the screw element engages between the pushing shaft and the plunger, resistance is optionally added against forward motion of the pushing shaft and/or the friction inhibiting rotation of the pushing shaft is optionally reduced. Optionally, the interface and/or the pushing shaft will rotate, engaging the screw threads. At some point of engagement of the screw threads (for example when they are fully screwed together and/or fully engaged), the resistance of the plunger to rotation will optionally stop and/or reduce rotation of the pushing shaft and/or facilitate further linear advance of the plunger and/or pushing shaft. Alternatively or additionally, a plunger interface may include a locking element, for example a plug and socket that transfers torque and/or linear force between the pushing shaft and the plunger. Alternatively or additionally, the plunger may include a ram interface with pushes the plunger without transferring significant rotational torque.

In some embodiments, a friction element may be adjusted according the drive system, injection schedule and/or load on the plunger. For example, for a high viscosity payload where the load on the injector is high, the friction element may be designed with lower friction resistance to forward movement. For example, where injection is fast (e.g. for a for a high pitch driving screw) the friction element may be designed with lower friction resistance to forward movement. For example, for a reservoir having approximately 100 g*cm of torque generated pushing the drug during delivery, a friction element may have a torque resistance in an non-preferred direction of approximately 90 g*cm and/or a plunger may have a torque resistance of approximately 60 g*cm such that the combined torque resistance in the non-preferred direction of the friction element and plunger may be approximately 150 g*cm. More generally, the torque resistance of the friction element in a non-preferred direction may range between 80 to 95% and/or between 65 to 80% and/or between 30 to 65% and/or between 5 to 30% and/or between 95 to 110% and/or between 110 to 175% and/or between 175 to 300% the torque generated by discharging the drug during delivery. The combined torque resistance in a non-preferred direction of the friction element and the plunger may range for example between 105% to 130% and/or 130% to 170% and/or between 170% to 250% and/or 250% to 500% the torque generated by discharging the drug during delivery. The torque generated discharging the drug during delivery may depend for example on the internal bore of an injection needle and/or on the cross sectional area of the reservoir and/or on the viscosity of the medicine and/or on a pitch of a driving screw. For example, for a 8.65 inner diameter reservoir with a 27G ultra thin wall delivery needle and a drug with viscosity between 30 to 50 cp, and an axial plunger speed of 1-3 cm/min, the axial force discharging the drug may be for example in the range between 0.2-3 kgf, the delivery torque discharging the drug during may range for example between 50-150 gr*cm torque on the screw. The combined torque resistance in a non-preferred direction of the friction element and the plunger may range for example between 50 to 300*gr·cm. For example as viscosity, the screw pitch, the cross sectional area increase and/or as the needle bore diameter decreases, the delivery torque may increase. Table 1 shows some approximate exemplary values for delivery torque (for example with an 8.65 inner diameter reservoir with a 27G ultra thin wall delivery needle). For example, the delivery torque discharging the drug during may range between 30 to 45 g*cm and/or between 45 to 70 g*cm and/or between 70 to 90 g*cm and/or between 90 to 130 g*cm and/or between 130 to 200 g*cm and/or between 200 to 1000 g*cm.

TABLE 1 examples of delivery torque for discharging the drug (not including friction of the friction element and the plunger with the wall of the reservoir) Torque Generated While Delivery Viscosity of Drug TSA pich 1 cp 30 cp 60 cp 0.75 mm 49.4 g * cm   74 g * cm 123 g * cm 0.85 mm 51 g * cm 86.5 g * cm   127 g * cm   1 mm 53 g * cm 86 g * cm 133 g * cm

In some embodiments, tradeoffs are possible. For example, for a higher viscosity drug, a lower pitch driving screw may be used and/or a higher friction anti-rotational pad may be used with a high pitch screw and/or a larger bore needle may be used. For example, the pitch of a driving screw may range between 3 mm to 1 mm and/or between 1 mm to 0.8 mm and/or between 0.8 mm to 0.6 mm and/or between 0.6 mm to 0.3 mm and/or between 0.3 mm to 0.2 mm.

In some embodiments, the friction element may be configured to reduce frictional resistance to axial advance of the pushing shaft. For example, the normal force between the friction element and the wall of the reservoir may be increased by tangential movement and/or decreased by axial movement. For example, the ratio of normal force during tangential movement to normal force during axial movement may range between 1.1 to 4 and/or between 4 to 10 and/or between 10 to 100 and/or more than 100. In some embodiments, the ratio of friction coefficient during tangential movement to the friction coefficient during axial movement may range between 1.1 to 4 and/or between 4 to 10 and/or between 10 to 100 and/or greater than 100.

In some embodiments, a friction element may include directional friction surface, for example micro nails and/or an embossed surface pattern and/or slanted hairs and/or scales and/or a non-isotropic molecular structure etc.

In some embodiments, after advancing in and unengaged state, the shaft may be engaged to a plunger.

DETAILED EMBODIMENTS

Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not necessarily limited in its application to the details of construction and the arrangement of the components and/or methods set forth in the following description and/or illustrated in the drawings and/or the Examples. The invention is capable of other embodiments or of being practiced or carried out in various ways.

Method of Facilitating Preferred Movement of a Plunger Driver

FIG. 1 is a flow chart illustration of a method of facilitating movement of a plunger pushing shaft in accordance with embodiments of the current invention. In some embodiments, a friction element may, for example, prevent the pushing shaft from rotating with respect to a reservoir thereby facilitating relative rotation between the pushing shaft and a driver element. Optionally, whenever the pushing shaft begins to rotate in an inhibited direction, friction between the pushing shaft and the reservoir increases. In some embodiments, friction is reduced when the pushing shaft advances. For example, reduction in friction may reduce a load on a drive system while pushing the plunger and/or discharging a drug.

In some embodiments, an immobile medicine reservoir may be supplied 102. For example, the reservoir may have a cylindrical cavity with a distal opening and/or a proximal opening. A plunger is optionally inserted in the cylindrical cavity. For example, the plunger may divide between a distal portion of the cavity containing the drug and the proximal portion of the cavity.

In some embodiments, a distal portion of a telescoping plunger pushing assembly may be inserted 104 into the proximal opening of the reservoir. For example, the distal portion of a telescoping plunger pushing assembly may include a pushing shaft and/or a distal portion thereof, a plunger interface and/or a friction element. Optionally a plunger interface of the pushing assembly will engage the plunger when the assembly is inserted 104. Alternatively or additionally, the plunger interface may remain disengaged from the plunger when the assembly is inserted 104 into the reservoir. In some embodiments, the distal end of the pushing assembly may be inserted 104 until it contacts the plunger. Alternatively or additionally, after insertion 104, the distal end of the pushing assembly may remain distanced proximally from the plunger.

In some embodiments, a friction surface may be retained 106 in contact with an interior wall of the reservoir and/or with the pushing shaft. For example, when the system is at rest, a radial element may keep at least a minimal normal force between the friction surface and the interior wall of the reservoir. For example, the radial element may be flexible and/or elastically compressible.

In some embodiments, a driving element may be rotated 108 in a first direction. Optionally the driving element may be engaged to the pushing shaft. For example, rotation 108 of the driving element may cause the pushing shaft to move 110. For example, the pushing shaft may tend to rotate 112 along with the driving element in the first direction. In some embodiments in may be desired to inhibit rotation 112 of the pushing shaft. For example, when telescoping is driven by relative rotation between the driving element and the pushing shaft, rotation 112 of the pushing shaft along with the driving element may be undesirable. Optionally, the friction element may be configured such that rotation 112 of the pushing shaft in the first direction wedges 114 the friction element and/or the radial element between the pushing shaft and the walls of the reservoir. Wedging 114 of the friction element between the driving shaft and the non-rotating reservoir optionally increases a normal force between the friction element and the walls of the reservoir and/or increases friction between the driving shaft and the reservoir and/or inhibits 115 rotation 112 of the pushing shaft.

In some embodiments, a set of screw threads may engage between the driver element and the pushing shaft. For example, rotation 108 of the driver element in the first direction with respect to the pushing shaft may advance 116 the pushing shaft distally into the reservoir. For example, advancing 116 may cause the pushing shaft to approach the plunger and/or cause the interface to engage the plunger and/or cause the plunger to advance distally. Optionally, the friction element and/or the radial element is configured such that advancing 116 the pushing shaft releases 118 a wedged element, for example the friction element and/or the radial element. Releasing 118 the wedged element optionally decreases a normal force between the friction element and the walls of the reservoir and/or decreases friction between the driving shaft and the reservoir and/or facilitates 119 advancing of the pushing shaft.

FIG. 2 is a flow chart illustration of a method of driving a plunger in accordance with embodiments of the current invention. Optionally, the plunger is driven by an advancing pushing shaft. For example, advancing of the pushing shaft may be motivated by relative rotation of a drive element with respect to a pushing shaft. Tangential friction between a friction element and the reservoir may supply counter rotational torque between the pushing shaft and the reservoir, facilitating relative rotation between the pushing shaft and the driver element. In some embodiments, the pushing shaft may advance in the reservoir while the pushing shaft is unengaged to the plunger. Optionally, while the pushing shaft and the plunger are unengaged, the tangential friction between the friction element and the reservoir may be substantially the only force preventing the pushing shaft from rotating along with the rotating element. In some embodiments, the friction element may be configured to produce increased resistance to an undesired movement (for example rotation with the driving element) and/or decreased resistance to a desired movement (for example advancing of the plunger).

In some embodiments, a distal portion of a plunger pushing assembly may be inserted 104 into a proximal opening of a drug reservoir. Optionally, the drug reservoir is rotationally immobile. Optionally, the drug reservoir includes a plunger separating between a drug in a distal portion of the reservoir and the proximal opening of the reservoir. Optionally, after insertion, a plunger interface of the pushing assembly may remain distanced proximally from the plunger. Optionally, the plunger interface is mounted on a distal portion of the pushing shaft.

In some embodiments, after the distal end of the plunger driving assembly is inserted 104 into the reservoir, a driving element may be engaged 207 to a power source. Alternatively or additionally, the driving element may be engaged 207 to the power source before being insertion 104 of the pushing assembly. For example, the power source may include an electric motor. The power source optionally rotates 108 the driving element in a first direction.

In some embodiments, during rotation 108 of the driving element in the first direction; the pushing shaft may be inhibited 214 from rotating by friction between a friction element and the inner wall of the reservoir. Optionally, rotation 108 of the driving element in the first direction relation to a pushing shaft causes the pushing shaft to telescope and/or move distally with respect to the driving element. For example, the pushing shaft and/or the plunger interface may be advanced 216 distally until it reaches the plunger.

In some embodiments, the plunger interface may engage 232 the plunger. For example, the plunger interface may transfer axial force between the plunger and the pushing shaft. In some embodiments, the plunger interface may limit rotation between the plunger and the pushing shaft. For example, after engagement of the plunger, friction between the plunger and the interior wall of the reservoir may prevent rotation of the pushing shaft in addition to and/or in place of the friction element. Alternatively or additionally, the plunger interface may allow rotation of the pushing shaft with respect to the plunger. Optionally, allowing rotation of the pushing shaft with respect to the plunger may reduce rotational stresses on the plunger.

In some embodiments, when the pushing shaft is advancing and/or when the plunger interface is engaged to the plunger, friction between the friction element and the wall of the reservoir may be reduced 218. Reducing the friction may make it easier to advance 216 the plunger driver and/or advance 234 the plunger.

Block Diagram of an Anti-Rotation System

FIG. 3A is a block diagram illustration of a drug reservoir and an assembly for driving a plunger in accordance with embodiments of the current invention. For example, plunger driving assembly may include a variable friction assembly 330 and/or a telescoping assembly including a proximal element 320 and/or a distal shaft 322 and/or a plunger interface 332. The telescoping assembly optionally telescopes via rotation of proximal element 320 (for example a driver element) with respect to distal shaft 322 (for example a plunger pushing shaft). For example, proximal element 320 may be rotated with respect to a drug reservoir 324 and/or distal element 322 is hindered from rotating with respect to drug reservoir 324. Optionally, distal element 322 is hindered from rotation by friction with the walls of reservoir 324. For example, friction with the walls of drug reservoir 324 may be supplied by variable friction assembly 330. For example, variable friction assembly 330 may have high resistance to rotation and/or tangential movement with respect to the drug reservoir and/or low resistance to axial translation with respect to the drug reservoir. Optionally, a motor 321 rotates proximal element 320 with respect to reservoir.

In some embodiments, variable friction assembly 330 may include a radial element 352 and/or a friction surface 331. Optionally, radial element 352 links friction surface 331 to distal shaft 322. Optionally, radial element 352 retains friction surface 331 in contact with an interior wall of reservoir 324.

In some embodiments, radial element 352 maintains a variable normal force between friction surface 331 and the interior wall of reservoir 324. For example, radial element 352 may be wedged between the interior wall of reservoir 324 and shaft 322 such that tangential movement of friction surface 331 in at least one direction causes compression of radial element (optionally increasing the normal force). Alternatively or additionally, radial element 352 may be wedged between the interior wall of reservoir 324 and shaft 322 such that axial movement of friction surface 331 in the distal direction causes release of compression of radial element (optionally decreasing the normal force). For example, the radial element may include one or more of a sprag, a virtual sprag, a beam having a preferred bending direction, a clutch dog, a wedge, a prop and/or a virtual beam having a preferred bending direction.

In some embodiments, radial element 352 may be wedged by movement in any of a plurality of directions. For example, radial element 352 may include a trapezoidal sprag that is wedged on one side by movement in one direction and on the other side by movement in an opposite direction. Alternatively or additionally, friction assembly 330 may include multiple anisotropic sprags and/or beams oriented in different directions to cause increased friction in more than one direction. For example, friction assembly 330 may have increased friction resistance to rotation around an axis in both rotational directions and/or have decreased friction to linear movement in one or more directions.

In some embodiments, friction surface 331 may have an anisotropic friction coefficient. For example, the friction coefficient may be high in one of the tangential directions optionally causing high friction resistance to rotation of the distal pushing shaft with respect to the reservoir in at least one direction and/or low friction resistance to movement distally with respect to the drug reservoir. Alternatively or additionally, the friction surface may have an isotropic coefficient of friction.

In some embodiments, proximal element 320 may be proximal to, partially inserted into and/or fully inserted into a proximal opening reservoir 324. In some embodiments, distal shaft 322 may be proximal to, partially inserted into and/or fully inserted into a proximal opening reservoir 324.

In some embodiments, reservoir 324 may contain a fluid, for example a drug 328. For example, drug 328 may be located in distal portion of reservoir 324. Optionally a plunger seal 326 may seal off and/or separate between drug 328 and the proximal opening of the reservoir and/or the plunger pushing assembly.

In some embodiments, when plunger interface 332 is engaged to plunger seal 326 it may supply a one-way, two-way or multi-dimensional connection between pushing shaft 322 and plunger seal 326. For example, plunger interface 332 may include a ram that supplies compression force between shaft 322 and plunger seal 326 for pushing plunger distally, but supplies small and/or negligible tensile force for pulling plunger seal 326 proximally. This ram may have friction surface with the plunger and/or partially intrude into the plunger. Alternatively, plunger interface 332 may include a snap, screw and/or interference element that supplies compression force between shaft 322 and plunger seal 326 for pushing plunger distally and also supplies tensile force for pulling plunger seal 326 proximally. In some embodiments, interface 332 transmits torque between plunger seal 326 and shaft 322. Alternatively or additionally, interface 332 may not transmit significant torque; for example interface 332 may include a pivot that allows shaft 322 to rotate independently of plunger seal 326.

FIG. 3B is a schematic diagram of a sprag 353 in accordance with an embodiment of the current invention. For example, in FIGS. 3B and 3C, sprag 353 is in contact with a surface 325. For example, in FIG. 3B surface 325 is moving in an inhibited direction indicated by arrow 388. Optionally, when surface 325 is moving in an inhibited direction, the angle of attack 386 between sprag 353 and the direction of movement will be less than 90 degrees. For example, the angle of attack may range between 89 to 85 degrees and/or between 85 to 70 degrees and/or between 70 to 45 degrees and/or between 45 to 0 degrees. Optionally, in some embodiments, a sprag may be anisotropic. For example, an angle of attach may differ on a leading and/or trailing edge. The movement of surface 325 optionally causes a rotational moment 384 on sprag 353 and/or wedges sprag 353 between the outer wall of a shaft 323 and surface 325. When movement is in the inhibited direction, rotational moment 384 and/or wedging optionally produces an increase 382 in the normal force of sprag 353 against surface 325. In some embodiments, when movement is in the inhibited direction, rotational moment 384 and/or wedging may produce an increase a force 383 of friction of sprag 353 against surface 325.

FIG. 3C is a schematic diagram of a sprag 353 in accordance with an embodiment of the current invention. For example, in FIG. 3C surface 325 is moving opposite an inhibited direction as indicated by arrow 388′. Optionally, when surface 325 is moving opposite an inhibited direction, the angle of attack 386′ between sprag 353 and the direction of movement will be greater than 90 degrees. For example, the angle of attack may range between 91 to 95 degrees and/or between 95 to 120 degrees and/or between 120 to 135 degrees and/or between 135 to 180 degrees. The movement of surface 325 optionally causes a rotational moment 384′ on sprag 353 and/or releases wedging of sprag 353 between the outer wall of a shaft 323 and surface 325. When movement is opposite the inhibited direction, rotational moment 384′ and/or releasing the wedging optionally produces a decrease 382′ in the normal force of sprag 353 against surface 325. In some embodiments, when movement is opposite the inhibited direction, rotational moment 384′ and/or releasing the wedging may produce a decrease in a force 383′ of friction of sprag 353 against surface 325.

Independent Anti-Rotation Sprags

FIGS. 4A-4F are drawings of a plunger driving assembly and drug reservoir with a screw-in plunger interface in accordance with embodiments of the current invention. In some embodiments, a multi sprag arm variable anti-rotation friction element 430 may supply rotational resistance to a pushing shaft (for example see pushing shaft 422 FIG. 4B). The anti-rotational friction may facilitate relative rotation and/or telescoping of pushing shaft 422 with respect to a driver (for example driver 420). For example pushing shaft 422 may be threaded and driver 420 may include a threaded element, for example a threaded shaft and/or a nut.

FIG. 4A illustrates a plunger driving assembly initially inserted into a proximal opening of a drug reservoir 424 in accordance with an embodiment of the current invention. In some embodiments, distal portion of the plunger driving assembly including for example a plunger interface 432 and/or variable resistance friction element 430 and/or a distal portion of pushing shaft 422. Optionally, when the plunger driving assembly is inserted, a plunger interface 432 remains distal to and/or disengaged from a plunger seal 426.

In some embodiments, a transmission gear 444, driver 420, a needle retraction lock 446 and a part of the proximal shaft 422 are located outside and/or proximal to reservoir 424. Optionally, the distal end of reservoir 424 includes a distal opening and a needle mount 442. The distal opening is optionally connected to a hypodermic needle 436. Optionally, the distal portion of reservoir 424 is filled with a drug 228. Plunger seal 426 separates and/or seals reservoir 424 between medicine 228 and a proximal portion and/or the proximal opening of the reservoir.

FIG. 4B illustrates a plunger driving assembly with the telescoping assembly beginning to open, advancing plunger interface 432 towards plunger seal 426 in accordance with an embodiment of the current invention. In some embodiments, after insertion, the telescoping assembly may be extended to advance interface 432 toward plunger seal 426 and/or to engage interface 432 to plunger seal 426.

In some embodiments, interface 432 is advanced by rotating transmission 444 and/or retraction lock 446 and/or driver 420 with respect to reservoir 424. Driver 420 is optionally threadably engaged to pushing shaft 422. In some embodiments, friction between friction element 430 and the inner walls of reservoir 424 inhibits rotation of pushing shaft 422 such that rotating driver 420 results in relative rotation between driver 420 and pushing shaft 422. Relative rotation of driver 420 and pushing shaft 422 optionally advances pushing shaft 422 and/or interface 432 towards plunger seal 426.

In some embodiments, interface 432 advances until it contacts plunger seal 426. When interface 432 contacts plunger seal 426, interface 432 may become linearly linked to plunger seal 426 (for example in that further linear advancement of interface 432 advances plunger seal 426) and rotationally independent of plunger seal 426 (in that rotation of interface 432 does not rotate plunger seal 426). In some embodiments, distal advancement optionally stops due to the normal force between interface 432 and plunger seal 426 and/or friction force between plunger seal 426 and the walls of reservoir 424 and/or the normal forces between drug 228 and plunger seal 426. Optionally, rotation of driver 420 while interface 432 does not advance overcomes friction between friction element 430 and the walls of reservoir 424 and/or causes rotation of interface 432. For example, rotation of interface 432 may screw it into plunger seal 426.

In some embodiments, when interface 432 is fully screwed into plunger seal 426, interface 432 becomes rotationally linked to plunger seal 426 (for example in that further rotation of interface 432 rotates plunger seal 426). In some embodiments, rotation of interface 432 optionally stops due to the combined frictional resistance to rotation of interface 432 and plunger seal 426 with respect to the walls of reservoir 424. Optionally, rotation of driver 420 while interface 432 does not rotate overcomes resistance to axial motion and/or plunger seal 426 begins to move axially and/or discharges the drug from the distal opening of the reservoir (for example through needle 436). In some embodiments, reservoir 424 may include a flange 438. For example, flange 438 may extend out from a rear portion of reservoir 424.

FIG. 4C is a close up perspective view of a distal end of a pushing shaft including a plunger interface 432 and a friction element 430 in accordance with an embodiment of the current invention. In some embodiments, an anti-rotation assembly may include a vent 450. For example, vent 450 may allow air to escape the zone between plunger seal 426 and interface 432 for example as interface 432 approaches plunger seal 426.

In some embodiments, a stabilizing base 440 may limit proximal movement of friction element 430 and/or determine the axial relationship of interface 432 and/or shaft 422 to friction element 430 and/or direct bowing and/or buckling of a radial element 452. For example, base 440 prevents radial elements 452 from buckling proximally and/or disengaging from the walls of reservoir 424. Optionally, there is a friction surface 431 on an external end of at least on radial element 452. For example, friction surface 431 may be held in contact with an interior wall of the reservoir.

FIG. 4D is a close up perspective view of a friction element 430 in accordance with an embodiment of the current invention. For example, element 430 is optionally a flexible disk shaped element with independent flexible radial elements 452, for example sprags. Optionally, each sprag includes a friction surface 431 for contacting the walls of reservoir 424. For example, each sprag is tilted off the radial direction towards the direction of inhibited movement. Optionally, friction surface 431 is on the outer end of the each radial element 452. For example, the outer end of each radial element 452 spread as it radiates outward and/or the outer end (head 453) of each sprag may be wider than its central end (stem 455).

In some embodiments, radial elements 452 are angled against an inhibited direction of rotation. For example, the inhibited direction of rotation may be the direction of rotation of driver 420 for extension of the telescoping assembly. Optionally, when driver 420 is rotating in a direction to expand the telescoping assembly (and/or advance pushing shaft 422) and frictional element 430 begins to rotate in the direction of rotation of driver 420, sprag type radial elements 452 get wedged against the walls of reservoir 424. Optionally, when driver 420 is rotating in a direction to expand the telescoping assembly (and/or advance pushing shaft 422) and frictional element 430 begins to rotate in the direction of rotation of driver 420 friction is increase between frictional element and reservoir 424 inhibiting the rotation of shaft 422 and/or facilitating relative rotation between driver 420 and shaft 422 and/or facilitating advancement of shaft 422. In some embodiments, a sprag 452 may be anisotropic. For example, the angle of attack of a leading edge 456 a may be steeper than the angle of attack of a trailing edge 456 b. For example, the mean angle of attack of sprag 452 may range between 80 and 90 degrees while the mean difference between the leading 456 a and trailing 456 b edges may range between 1 and 9 degrees. For example, the mean angle of attack of a sprag may range between 60 and 80 degrees while the mean difference between the leading and trailing edges may range between 1 and 40 degrees. For example, the mean angle of attack of a sprag may range between 20 and 60 degrees while the mean difference between the leading and trailing edges may range between 1 and 70 degrees.

In some embodiments, friction element 430 may be made of rubber, elastomer and/or silicone for example of hardness shore 00 scale approximately 50. For example, the hardness may range between shore 00 scale 10 to 30 and/or 40 to 60 and/or 60 to 100 and/or shore A scale 60 to 100. Optionally, the unstressed diameter of friction element 430 is slightly larger than the inner diameter of reservoir 424. For example, the unstressed outer diameter of element 430 may be approximately 9.1 mm while the inner diameter of reservoir 424 may be approximately 8.65 mm. Optionally, the inner diameter of a reservoir may range between 1 to 4 mm and/or between 4 to 7 mm and/or between 7 to 10 mm and/or between 10 to 15 mm and/or between 15 to 30 mm. Optionally, the outer diameter of a friction element may range between 100% to 103% and/or 103% to 107% and/or 107% to 120% and/or 120% to 150% the internal diameter of the reservoir. In some embodiments, friction element 430 may have a closed diameter at the base (stem 455) of sprags 452 of approximately 6.3 mm and/or the length of sprags 452 (in the radial direction) may be approximately 1.4 mm. For example, the thickness (along the length of reservoir 424) of element 430 and/or sprags 452 may be 2 mm and/or radial length of the head of sprags 452 may be approximately 1.65 mm and/or the surface 431 area of each sprag 452 in contact with the inner wall of reservoir 452 may be approximately 2+1.65=3.3 mm². In some embodiments, the length of a sprag element may range for example between 1 and 10% the diameter of the reservoir and/or between 10 to 20% the diameter of the reservoir and/or between 20 to 40% the diameter of the reservoir and/or between 40 to 70% the diameter of the reservoir and/or between 70 to 100% the diameter of the reservoir. In some embodiments, the width of a friction element may range for example between 1 to 5% and/or between 5 to 15% and/or between 15 to 25% and/or between 25 to 50% and/or between 50 to 75% and/or between 75 to 150% and/or between 150 to 600% the diameter of the friction element.

In some embodiments, friction element 430 may include a mount for connection to pushing shaft 422 and/or to interface 432. For example, shaft mount 454 of friction element 430 includes an internally threaded aperture that threadably mates to an external threads 462 of plunger interface 432 (see for example FIG. 4E).

FIG. 4E is a close up perspective view of plunger interface 432 in accordance with an embodiment of the current invention. For example, interface 432 is optionally a hard element (for example made of molded plastic) with a tapered screw thread 462 for attaching to plunger seal 426 and/or friction element 430. Optionally, interface 432 includes a tapered distal face 466 and/or a proximal base 440 and/or a vent 450. Optionally vent 450 includes a slit in base 440. Optionally, slit 450 is positioned to align with a space between radial elements 452. Alternatively or additionally, a friction element may include a vent. For example, when the friction element is mounted on interface 432, the vent of the friction element may be aligned with vent 450.

In some embodiments, friction element 430 may include a mount for connection to pushing shaft 422 and/or to interface 432. For example, shaft mount 454 of friction element 430 includes an internally threaded aperture that threadably mates to an external threads 462 of plunger interface 432 (see for example FIG. 4E).

FIG. 4F is a cross sectional view of friction element 430 mounted on an adapter 432 in accordance with an embodiment of the present invention. For example, screw threads 462 are smaller at the insertion point (the distal end) and grow as one moves proximally. The rear (proximal) face of the teeth is optionally at a sharper angle (for example between 70 to 95 degrees from the axis of adaptor 432) than the front (distal) face of the teeth (which range for example at an angle between 115 to 145 degrees from the axis of adaptor 432).

Linear Motion Sensitive Sprags

FIG. 5 is a perspective drawing of a plunger pushing rod and friction element for facilitating forward linear motion in accordance with embodiments of the current invention. Optionally, friction element 530 is angled backwards (for example proximally). For example, advancement of shaft 422 the angle of attack of element 530 would be greater than 90 degrees. Optionally, advancement of shaft would reduce the normal force and/or the friction between friction element 530 and the wall a reservoir 424. Optionally, when shaft 422 is rotating but not advancing, the friction between element 530 and reservoir 424 is high, inhibiting rotation. Optionally, as shaft 422 advances in reservoir 424, the shape of element 530 causes a reduction in friction facilitating the advancement.

Friction Disk with Anti-Rotation Beam

FIG. 6A is cross sectional view of a plunger pushing rod including flexible beam anisotropic friction elements in accordance with embodiments of the current invention. In some embodiments, a friction element 630 may include an anisotropic bending beam 652. For example, when beam 652 is bent in an inhibited direction it may not bend away and/or it may get wedged between a plunger interface 632 and the walls of reservoir 424. For example, when beam 652 is bent in a non-inhibited direction, beam 652 may bend out of the way and/or reduce friction. In FIG. 6A elements 652 are illustrated in a relatively unstressed state.

In some embodiments, a beam may have anisotropic compressibility and/or extensibility. For example, beam 652 has a cut out section 672. The side of the beam with the cut out extends and/or compresses more easily than the opposite side.

FIG. 6B illustrates element 652 in a stressed state due to rotation of interface 632 in an inhibited direction 678 in accordance with an embodiment of the present invention. Optionally, when element 652 is stressed, cut out section 672 may tend to expand and/or contract while uncut side of the beam may tend to buckle and/or bend. Optionally, stress due to rotation in the inhibited direction 678 causes cut out section 672 to open wedging surface 631 against reservoir 424 increasing a normal force and/or a friction between surface 631 and reservoir 424.

Pressure Sensitive Friction Element

FIGS. 7A-7B are side views of a plunger pushing assembly with reduced friction when engaged to a plunger in accordance with embodiments of the current invention. For example, a friction element 730 may be sized to contact a wall of a drug reservoir and/or produce friction with the wall inhibiting rotation of a plunger pushing shaft 422 and/or a plunger interface 732. Optionally, when interface 732 engages a plunger 726, friction between element 730 and the reservoir may be reduced and/or the resistance to advancement of the plunger may be reduced.

FIG. 7A illustrates plunger interface 732 and friction element 730 while disengaged from a plunger in accordance with an embodiment of the current invention. In some embodiments, shaft 422 may be advanced through reservoir 424 by rotation of a driver relative to shaft 422. As interface 732 approaches plunger 726, friction element contacts the interior walls of reservoir 424 and/or inhibits rotation of shaft 422 and/or facilitates the relative rotation of the driver with respect to shaft 422.

FIG. 7B illustrates plunger interface 732 and friction element 730 while engaged to a plunger in accordance with an embodiment of the current invention. In some embodiments, when interface 732 engages plunger 726, an element (for example the hard side walls of the plunger and or a bowl shaped and/or annular projection) deform friction element 730. Deformation of friction element 730 optionally reduces and/or eliminates contact between friction element and reservoir 424. For example, deformation of friction element 730 may reduce and/or substantially nullify friction between element 730 and reservoir 424. Optionally, when plunger interface 732 is engaged with plunger 726, friction between plunger 726 and reservoir 424 may inhibit rotation of shaft 422 and/or facilitate advance of shaft 422 and/or plunger 726. In some embodiments, reduction of the friction between element 730 and reservoir 424 may reduce the load on a plunger pushing assembly. For example, interface 732 may be engaged to plunger 726 while a device is discharging a drug. Reduction of friction between element 732 and reservoir 424 optionally reduces the load on the plunger pushing system while discharging the drug.

In some embodiments, advancement of the plunger pushing assembly may proceed through a few friction stages and/or configurations. For example, while interface 732 is distanced proximally from plunger 726, the resistance to rotation caused friction between element 730 and reservoir 424 may be enough to prevent rotation of shaft 422. With shaft 422 rotationally immobile, rotation of a driver may produce relative rotation between the driver and shaft 422 and/or advancement of shaft 422.

In some embodiments, shaft 422 advances until interface 732 contacts the proximal side of plunger 726. Once interface 732 contacts the proximal side of plunger 726 rotation of the driver and resistance to rotation by friction element 730 may be enough to overcome resistance to advance of plunger 726. Subsequently, interface 732 is driven forward, driving forward plunger 726 and discharging the medicine. Alternatively or additionally, when interface 732 contacts the proximal side of plunger 726, resistance to advance of plunger 726 may be enough to stop advance of shaft 422. While resistance of plunger 726 prevents advance of interface 732, torque optionally overcomes rotation resistance of element 730. For example, overcoming rotational resistance may cause interface 732 to rotate and/or be screwed into the proximal end of plunger 726 and/or engage plunger 726.

In some embodiments, once interface 732 is engagement of interface 732 to plunger 726 may prevent rotation of interface 732 with respect to plunger 726. Friction between plunger 726 and reservoir 424 may prevent further rotation of shaft 422, facilitating relative rotation of shaft 422. Prevent rotation of interface 732 optionally facilitates rotation a driver in relation to shaft 422 optionally facilitating further advance of plunger seal 426.

Plunger Interface

FIG. 8 is a perspective view of a plunger pushing rod including a sprag friction elements and a ram plunger interface in accordance with embodiments of the current invention. In some embodiments, a plunger interface will transfer linear forces between a plunger and a pushing shaft 422. Optionally, the interface will transfer limited or negligible rotational torque between the plunger and the pushing rod. For example, a ram 832 may push a plunger along an axis of a drug reservoir (for example distally). Ram 832 may transfer little or no torque around the axis. For example, embodiments, ram 832 may not be rotationally fixed to shaft 422 and/or to the plunger. Torque is optionally transferred between shaft 422 and the plunger by friction. Alternatively or additionally, there may be a rotating element (for example a pivot and/or an axel) between shaft 422 and ram 832 limiting transfer of torque. Optionally, rotational resistance of friction element 830 will be high enough to prevent a driver from rotating shaft 422 under the dual load of linear resistance of friction element 830 and the plunger (resistance to linear movement of the plunger may include for example friction between the plunger and the reservoir and/or resistance to discharge of the drug).

Friction Disk with Anti-Rotation Sprag Ribs

FIG. 9 is a perspective view of a friction element 930 including virtual sprag friction elements in accordance with embodiments of the current invention. In some embodiments, a radial element 952 may be constructed of angled layers of connected sheets 992. Sheets 992 are optionally angled toward the inhibited direction 996 of rotation. When the periphery of element 930 are in frictional contact with an immobile reservoir wall, rotation of element 930 in the inhibited direction 996 optionally spreads sheets 992 and/or increase a surface area of friction. Alternatively or additionally, rotation in the inhibited direction 996 pushes against joints 994 which are virtual sprag elements that are optionally stiffer than the sheets, for example increasing a normal force between friction element 930 and a wall of a reservoir. Alternatively or additionally, virtual sprag elements may include a thickened rib angled against the inhibited direction and/or a rib of a stiffer material than the rest of the disk angled against the direction of inhibited movement. Optionally, friction element 930 optionally includes a shaft mount 954.

Friction Element with Rollers

FIG. 10A is a perspective view of a friction element 1030 a including rolling element 1051 in accordance with embodiments of the current invention. For motion in the preferred direction, rolling element 1051 may roll, allowing motion with minimal friction whereas for motion in the non-preferred direction. For example, friction element 1030 a may move axially inside reservoir 424 with a friction force of a hundredth or less than the force necessary to rotate element 1030 a around the axis of reservoir 424. For example, a rolling element may be round and/or spherical and/or cylindrical and/or tapered. A rolling element may include a wheel and/or an axel and/or a bearing and/or a race and/or a cage.

In some embodiments, for example as illustrated in FIG. 10B, rolling element 1051 may include a wheel 1052. For example, during movement in a preferred direction, for example as element 1030 b moves linearly along the axis of reservoir 424, wheel 1052 may rotate around an axel 1055. Optionally, a rolling element may be inside an indentation and/or a ball cage 1091. For example, cage 1091 optionally includes an indentation in a connecting element 1089 b. For example, connecting element 1089 b may include a disk and/or cylindrical connector between a drive screw and/or a plunger adapter. Alternatively or additionally, friction element may be built into a driving element and/or a plunger adapter. For example, a wheel and/or an axel and/or a race and/or a cage may be built into the plunger adapter and/or the drive element.

Some embodiments of an anti-rotational element 1030 b, a connecting element 1089 b may include a shaft mount 1054, for example as illustrated in FIG. 10B. Additionally or alternatively, in some embodiments of an anti-friction element 1030 c, a connecting element 1089 c may not have a shaft mount, for example as illustrated in FIG. 10C. For example, connecting element fit between a driving shaft and/or a plunger.

Friction Element Preventing Rotation of Reservoir

FIG. 11 is a perspective view illustration of a drug reservoir with an external anti-rotational friction element in accordance with an embodiment of the present invention. Optionally, an external friction element 1130 resists rotation of the reservoir with respect to a housing of a drug delivery device. For example, friction element 1130 has anisotropic friction with higher frictional resistance against movement in a non-preferred direction than in a preferred direction. For example, sprags 452 have enhanced friction to resist rotation of reservoir 1124 in a non-preferred direction. Optionally, reservoir can easily be slid longitudinally into element 1130, but once in place is difficult to move in a non-preferred direction (for example to rotate against sprags 452 and/or to remove reservoir 1124).

In some embodiments, element 1130 may have the form of a ring surrounding reservoir 1124. Optionally, sprags 452 radiate inward from the ring towards the outer wall of reservoir 1124.

In some embodiments, a system may include two directionally preferential friction elements. For example, friction element 430 may prevent rotation of a plunger driving shaft. For example, element 430 facilitates movement of a plunger driver by a shaft driver 1120. In some embodiments, sprags 452 of internal friction element 430 are oriented in the opposite direction from sprags 452 of external friction element 1130. For example, friction element 430 may prevent a plunger driver from rotating by applying a first torque in a first non-preferred direction (non-preferred with reference to inner element 430) to an inner wall of reservoir 1124. Optionally, element 1130 may prevent rotation of reservoir 1124 by providing an opposite torque to the outer wall of reservoir 1124. The second torque may inhibit rotation of reservoir 1124 in a second non-preferred direction. In some embodiments, the first and second non-preferred directions may be opposite in orientation.

In some embodiments, external friction element 1130 may include anchors 1157 to hold it in a drug delivery device. For example, anchors 1157 are protrusions molded into element 1130 that fit into indentations on the inner wall of a casing of a drug delivery device (for example casing 1259 as illustrated in FIG. 12B). Optionally, anchors 1157 inhibit movement of element 1130 with respect to the drug delivery device. Optionally, other means may be used to stabilize element 1130 with respect to a delivery device, for example glue and/or other sorts of anchors and/or fittings.

FIG. 12A is a perspective view illustration of a drug reservoir with an alternative external anti-rotational friction element 1230 in accordance with an embodiment of the present invention. Optionally, element 1230 only partially surrounds reservoir 1124. Element 1230 is optionally molded in one step with other elements of a drug delivery device. For example, element 1230 includes an elastomeric button cover 1257 for the delivery device.

FIG. 12B illustrates an internal view of friction element 1230 installed into a top half of a casing 1259 of a drug delivery device. Element 1230 optionally serves to inhibit rotation of reservoir 1124. Optionally, cover 1257 seals a hole in casing 1259 providing a water tight seal. The hole optionally provides access for a user to push an activation button of the device.

Optionally, an outer friction element may include various anisotropic friction elements as described herein above for example a sprag and/or an anisotropically bending beam and/or a clutch dog and/or a virtual element and/or an anisotropic friction surface. Friction to inhibit rotation of the reservoir may optionally be provided by multiple elements.

Exemplary Dimensions of a Drug Delivery Device

In some embodiments, the payload of a reservoir (for example a syringe) may include, for example between 0.5 and 2 ml and/or between 2 and 4 ml and/or between 4 and 5 ml of a drug and/or more. In some embodiments, the injector may discharge the entire payload as a single dose. A drug delivery device may include, for example, a pen injector, and/or an internally powered driver to drive the plunger and/or discharge the payload. For the sake of this application, an internally powered injector driver may be defined as a drive mechanism powered by energy stored at least temporarily within the injector. Power may be stored in a power supply, for instance as chemical potential (for example a chemical that produces an expanding gas and/or a battery) and/or mechanical potential (for example stored in an elastic member and/or a spring and/or torque spring and/or a pressurized gas). For example, the driver may be designed to discharge the payload over a time period ranging between 20 and 120 seconds and/or between 120 and 600 seconds and/or longer. In some embodiments, discharge may be driven by a driver. An internally powered driver may be powered by various mechanisms including for example a motor (including for example a DC motor, an actuator, a brushless motor) and/or a transmission including for example a telescoping assembly and/or a threaded element and/or a gear and/or a coupling and/or an elastic mechanism (for example a spring and/or a rubber band) and/or an expanding gas and/or a hydraulic actuator).

A drug delivery device in accordance with some embodiments of the current invention may include reservoir. For example, a reservoir may include a medicine container and/or a standard type syringe. Optionally, a standard type syringe may be preloaded with medicine using standard equipment and/or in an aseptic room. A preloaded standard type syringe may optionally include a proximal opening. A plunger may optionally seal the proximal opening and/or protect the sterility of the contents of the syringe. A sterile needle (for example a hollow needle) may optionally be connected to the syringe barrel. For example, the hollow of the needle may be in fluid communication with the interior of the barrel. The needle may optionally be rigidly attached to the distal end of the barrel. The sterility of all and/or part of the needle may for example be protected by a sterile cover. The sterile cover may remain on the needle when the syringe is supplied and/or installed into an injector. For example, the medicine container may optionally include a cylindrical barrel rigidly attached to a needle. Optionally, the long axes of the needle and barrel of the syringe may be parallel and/or coaxial. Optionally, the needle may be mounted on the distal end of the barrel. Optionally, the needle point may be pointing in the distal direction. In some embodiments, a plunger may slide axially along the inside of the barrel to discharge a medicine payload. For example, the medicine may be discharged through the hollow needle.

In some embodiments, the force to insert the needle to the skin of a patient may range for example between 0.02 to 0.2 N and/or between 0.2 and 0.5 N. Optionally, the force required to inject the drug (for example the force on a syringe plunger) may range for example between 5 to 60 N. For example, the force required to inject the drug may depend on the injection rate and/or the viscosity of the drug and/or the syringe geometry and/or the needle dimensions.

For example, in the event of an occlusion and/or at the end of delivery, the linear force generated by the device may increase to the level of up to 60 N. A needle safeguarding mechanism (for example a needle retraction mechanism) may be sensitive to the force. For example, mechanism may include a snap that gives way at 40 N returning the needle to the retracted position. In some embodiments, a needle protection mechanism may be triggered by a linear force greater than, for example, between 10 to 60 N.

In some embodiments, the stress to inject a medicine and/or to trigger safeguarding of a needle may include a torque. For example, injection of medicine may be driven by a plunger. The plunger may optionally be driven by a threaded assembly, for example a threaded screw and/or teeth and/or a telescoping assembly. Optionally, the pitch of the teeth and/or an associated screw may range for example between 0.5 and 2 mm. The diameter of the screw may range for example between 3 and 15 mm. The torque to power injection may range for example between 0.2 and 1.0 N*cm. The trigger torque (the torque at which the needle safeguarding is triggered) may range for example between to 0.5 to 2 and/or from 2 to 4 and/or from 4 to 10N*cm.

During injection, the linear movement of a plunger may range for example between 10-50 mm. The length of movement of the plunger may vary for example with the volume of medicine to be injected that may range for example between 0.5 to 3 ml.

In some embodiments, discharge may be driven by a torque. For example, the driver may apply torque to threaded element pushing a plunger. In some embodiments, a time of discharge may depend on the fill volume and/or viscosity. For example, the expected injection speeds may be Injection speed depend on viscosity, for example for viscosity ranging from 1 cp to 15 cp the expected injection rage may range between 30 to 40 sec/1 ml, for example for viscosity ranging from 15 cp to 60 cp the expected injection rate may range between 35 to 60 sec/ml for viscosity above 60 cp the expected injection rate may range between 53 to 67 sec/1 ml. The maximum and/or minimum expected injection time may for example be the maximum and/or minimum allowed fill volume divided by an injection rate. For example an expected time of discharge may range for example between 24 to 48 seconds (for example for between 0.8 and 1.2 ml of fluid having a viscosity ranging between 1 to 15 cp) and/or between 36 to 68 seconds (for example for between 1.2 and 1.7 ml of fluid having a viscosity ranging between 1 to 15 cp) and/or between 51 to 92 seconds (for example for between 1.7 and 2.3 ml of fluid having a viscosity between 1 to 15 cp) and/or between 70 to 150 seconds (for example for 2.0 to 2.5 ml of fluid having a viscosity of between 15 and 40 cp) and/or between 120 seconds and 3 minutes for larger volumes and/or viscosities.

In some embodiments, the drug delivery device may be configured to operate independently and/or be handheld. For example, the device may have a weight ranging between 10 grams to 30 grams and/or between 30 grams to 150 grams and/or between 150 grams to 500 grams. Optionally, the drug may be contained within the device. Optionally, the fluid path of the drug from the reservoir to the injection needle may be within the device. Optionally, the power supply may be within the device. Optionally, the device may be operable with one hand.

It is expected that during the life of a patent maturing from this application many relevant technologies will be developed and the scope of the terms are intended to include all such new technologies a priori.

As used herein the term “about” refers to ±5%.

The terms “comprises”, “comprising”, “includes”, “including”, “having” and their conjugates mean “including but not limited to”.

The term “consisting of” means “including and limited to”.

The term “consisting essentially of” means that the composition, method or structure may include additional ingredients, steps and/or parts, but only if the additional ingredients, steps and/or parts do not materially alter the basic and novel characteristics of the claimed composition, method or structure.

As used herein, the singular form “a”, “an” and “the” include plural references unless the context clearly dictates otherwise. For example, the term “a compound” or “at least one compound” may include a plurality of compounds, including mixtures thereof.

Throughout this application, various embodiments of this invention may be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.

Whenever a numerical range is indicated herein, it is meant to include any cited numeral (fractional or integral) within the indicated range. The phrases “ranging/ranges between” a first indicate number and a second indicate number and “ranging/ranges from” a first indicate number “to” a second indicate number are used herein interchangeably and are meant to include the first and second indicated numbers and all the fractional and integral numerals therebetween.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination or as suitable in any other described embodiment of the invention. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements.

Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.

All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention. To the extent that section headings are used, they should not be construed as necessarily limiting. 

What is claimed is:
 1. An assembly for driving a plunger and in a drug reservoir, the plunger dividing between a drug in a distal portion of the reservoir and a proximal opening of the reservoir; the assembly comprising: a telescoping shaft that extends by rotation of a driving element in a first rotational direction with respect to a distal shaft; a distal end of said distal shaft configured to engage the plunger; and a radial element extending from said distal shaft to contact an interior side wall of the reservoir, said element configured and oriented to wedge between said interior wall and said distal shaft when said distal shaft is rotated in said first rotational direction.
 2. The assembly of claim 1, wherein said element includes a virtual sprag having a long axis and wherein said long axis intersects said interior side wall.
 3. The assembly of claim 2, wherein said long axis intersects said interior side wall at an angle between 91 and 120 degrees from said first rotational direction.
 4. The assembly of claim 1, wherein said element includes a virtual beam having a preferred bending direction opposite said first rotational direction.
 5. The assembly of claim 1, further comprising: a plunger interface configured to engage the plunger; said plunger interface irrotationally interconnecting said distal shaft and the plunger when said plunger interface is engaged to the plunger.
 6. The assembly of claim 1, further comprising: a vent for releasing gas from a space between the element and the plunger.
 7. The assembly of claim 1, wherein said radial element is located proximal to said distal end of said distal shaft.
 8. The assembly of claim 1, wherein said wedging is longitudinal such that moving said distal shaft distally with respect to said reservoir reduces a normal force between said radial element and said interior wall.
 9. The assembly of claim 1, wherein a resistance due to friction between said radial element and said interior wall to movement of said distal shaft in said first rotational direction is higher resistance due to friction between said radial element and said interior wall to movement of said distal shaft in a direction opposite said first rotational direction.
 10. The assembly of claim 1, further comprising: a second friction element extending from a drug delivery device to contact an exterior side wall of the reservoir when said reservoir is inserted into said drug delivery device, said second friction element is configured and oriented to wedge between said exterior wall and said reservoir when said reservoir is rotated in a second rotational direction.
 11. The assembly of claim 10, wherein said second rotational direction is opposite said first rotational direction.
 12. A method of advancing a plunger in a drug reservoir comprising: providing a telescoping assembly that extends by rotating a driver in a first direction with respect to a pushing shaft mated to the driver, said pushing shaft including a friction element in contact with a wall of the reservoir; rotating said driver in said first direction; wedging said friction element between said pushing shaft and said wall as result of said rotating; inhibiting rotation of said first direction as a result of said wedging; and unwedging said friction element to facilitating advancing of said pushing shaft.
 13. The method of claim 12, wherein said wedging is substantially the only process impeding rotation of said pushing shaft with respect to the reservoir.
 14. The method of claim 12, wherein wedging include increasing normal force.
 15. The method of claim 12, further comprising: reducing a normal force between said friction element and said wall of the reservoir when said pushing shaft moves in a distal direction.
 16. The method of claim 12, wherein the drug reservoir includes a plunger, the method further comprising: reducing a normal force between said friction element and said wall of the reservoir when said pushing shaft pushes distally against said plunger.
 17. A drug delivery device comprising: a housing including a channel; a drug reservoir fitting into said channel; and a friction element extending from a housing to said channel to contact an exterior side wall of the reservoir when said reservoir is inserted into said channel, said element configured and oriented to wedge between said exterior wall and said reservoir when said reservoir is rotated in a first rotational direction.
 18. The assembly of claim 17, further comprising: a telescoping shaft that extends by rotation of a driving element in a first rotational direction with respect to a shaft; and a second friction element inhibiting rotation of said shaft with respect to said reservoir.
 19. The assembly of claim 17, wherein said channel is cylindrical and includes an opening at one end and wherein said reservoir slides longitudinally through said opening into said channel and wherein said friction element has increased friction resistance to movement in said first rotational direction than to movement in said longitudinal direction.
 20. A method of distributing a drug comprising: supplying a reservoir containing the drug and a distribution device including a channel and a friction element; inserting said reservoir into longitudinally into said channel; and wedging said reservoir against said friction element by rotating said reservoir with respect to said device. 